Description

The hardened series contained features like ASan that helped us spot problems in our code earlier. We want to have similar nightly builds when switching to rbm. The tor-browser code still contains .mozconfig-asan which should be usable and I guess there are other things that can get salvaged from the descriptors in the hardened-builds branch as well.

1)
The resulting bundle does not start for me due to wrong file permissions:

-rw------- 1 thomas thomas 12930 Jan 1 2000 Browser/start-tor-browser

2)--enable-expensive-hardening is deprecated. We should use --enable-fragile-hardening instead for tor. See: #21290 for more details and commit 5335a8e6f8317ea3645227d139369f8931cdb299 for the actual change.

Thanks. One final thing. I am a bit wary to start collecting Firefox patches in tor-browser-build. While I think there could be an argument made for the #23231 workaround (who really is using plain tor-browser.git to cross-compile stuff for Windows??) I think it does not hold for the ASan case. We are shipping a .mozconfig-asan file and, in fact, if one uses Linux and wants to do dev work there is no need to use an rbm build for that. Thus, let's keep the workaround for #21925 in tor-browser.git. There should not be any breakage for the non-ASan series regardless the platform we compile for. And it would make the tor-browser-build patch simpler.